At least one example embodiment provides a system comprising a three-phase direct-current-to-direct-current converter (DC-DC converter) including a three-phase primary converter coupled to a three-phase secondary converter via at least one transformer; and a controller configured to cause the system to, obtain a load curve based on an operational load ratio or percentage of the three-phase DC-DC converter, the load curve associated with at least one phase of the primary converter and the secondary converter, and adjust or maintain a modulation frequency of the at least one phase of the primary converter and the secondary converter consistent with an operation point on the obtained load curve.